Motion picture camera drive mechanism

ABSTRACT

A motion picture camera drive mechanism includes a single motor which is used for driving (separately or simultaneously) a film pull down mechanism which advances film past an exposure aperture and a mechanism for adjusting at least one lens element in a zoom lens system. When the camera drive mechanism is to be energized, provision is made for first energizing a circuit to an automatic exposure control system and then operating the film pull down mechanism, thereby effecting correct exposure of the first frame of film.

United States Patent [1 1 Jenkins et al.

[62] Division of Ser. No. 168,221, Aug. 2, 1971, Pat. No.

[52] U.S. Cl. 352/174, 352/178 [51] Int. Cl. G03b 1/00 [58] Field ofSearch 352/174, 178

[56] References Cited UNITED STATES PATENTS 3,476,471 11/1969 Marvin352/178 MOTION PICTURE CAMERA DRIVE MECHANISM Inventors: Gerald L.Jenkins; Vernon H.

Jungjohann; Edgar S. Marvin, all of Rochester; Neil G. Seely, Brockport,all of NY.

Eastman Kodak Company, Rochester, N.Y.

Filed: Sept. 15, 1972 Appl. No.: 289,516

Related U.S. Application Data Assignee:

[ 1 Oct. 30, 1973 3,427,103 2/1969 McCain 352/178 3,512,881 5/1970Kubota 352/178 X 3,475,090 10/1969 Easterly 352/174 PrimaryExaminer-Monroe l-I. Hayes Att0meyW. H. .I. Kline [57] ABSTRACT A motionpicture camera drive mechanism includes a single motor which is used fordriving (separately or simultaneously) a film pull down mechanism whichadvances film past an exposure aperture and a mechanism for adjusting atleast one lens element in a zoom lens system. When the camera drivemechanism is to be energized, provision is made for first energizing acircuit to an automatic exposure control system and then operating thefilm pull down mechanism, thereby effecting correct exposure of thefirst frame of film.

3 Claims, 10 Drawing Figures Patented Oct. 30, 1973 '7 Sheets-Sheet 1 31NE 09 m! 41 Patented 0a. 30, 1973 7 Sheets-Sheet 2 #3 m3 N9 09 N! m3Patented Oct. 30, 1973 7 Sheets-Sheet 31 m2 NE 02 NE Patented Oct. 30,1973 '7 Sheets-Sheet 4 7 Sheets-Sheet 5 Patented Oct. 30, 1973 3,768,896

7 Sheets-Sheet f;

FIG.7

SWIM

Patented Get. 30, 1973 3,768,896

7 Sheets-Sheet 7 1 MOTION PICTURE CAMERA DRIVE MECHANISM BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates generallyto drive mechanisms for motion picture cameras or the like and, morespecifically, to such a drive mechanism which utilizes a single motorfor simultaneously or independently driving both the film advancingmechanism and an adjustable zoom lens system.

2. Description of the Prior Art Various mechanisms for driving a filmpull down claw and adjusting a zoom lens in a motion picture camera arewell known to the art. For example, U.S. Pat. No. 2,995,061 entitledMechanism for Adjusting Zoom Lens Assembly, issued Aug. 8, 1961 toBriskin et al. discloses a camera with a zoom lens assembly wherein thezoom lens is driven in one direction by engaging a first gear with arack coupled to a movable element of a zoom lens. The zoom lens isdriven in the opposite direction by engaging a second gear with therack. This patent also discloses alternate means for effecting manualadjustment of the zoom lens system independently of the motor, therebypermitting nonpowered adjustment of the zoom lens system when the filmpull down mechanism is not being operated. U.S. Pat. No. 3,157,881 forZoom Lens Drive Mechanisms for Photographic Cameras, issued to G. L.Jenkins et al.

on Nov. 17, 1964, relates to a drive mechanism for both a film pull downor advance device and zoom lens adjusting means for a motion picturecamera. The device disclosed in the Jenkins et al patent drives both thefilm advance mechanism and the lens adjustment mechanism from a singlemotor, and uses a slip clutch between the motor and drive for the pulldown mechanism to permit separate and independent operation of the zoommechanism from the camera motor during periods when film is not beingadvanced through the camera. Also, U.S. Pat. No. 3,106,125 for a ZoomLens Drive Mechanism, issued- Oct. 8, 1963 to W. A. Martin et aldiscloses another motion picture camera having a single drive motor foroperating both the zoom lens mechanism and film advance means in thecamera. The mechanism disclosed in the latter patent utilizes a pair ofarms linked to the adjustable lens in a zoom lens system, and camfollowers on the arms which are selectively engaged in spiral grooves onopposite faces of a cam rotated by the camera drive motor. ,These andother known camera drive mechanisms suffer from one or moredisadvantages including, inter alia, the need to provide for separatemanual adjustment of the zoom mechanism when the film advancemechanismis not being operated, and the need for spenism is initiated in order toinsure proper exposure of even the first frame during a sequence offilming. These and other disadvantages have been overcome by the presentinvention.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an improved drive mechanism for a motion picture camera having asingle motor wherein the zoom lens system and the film advance means inthe camera can be operated independently or simultaneously.

A further object of the invention is to provide such a drive mechanismwhich is easily adjustable to effect two different rates of advance offilm through the camera.

Another object of the invention is to provide a drive mechanism for usewith a camera having an exposure control system wherein the exposurecontrol system normally is energized first and then, after a slight timedelay, the film advance means is energized; and to such a drivemechanism wherein the film advance means can be energized first undercertain conditions.

In accordance with a preferred embodiment of the present invention, adrive mechanism is provided for a motion picture camera having a motoradapted to drive a lens system having at least one lens element mountedon the camera for movement along an axis in each of two oppositedirections for varying the magnification of the lens system. The camerahas film advance means coupled to the motor and adapted to beselectively coupled to the cam for driving the cam and thereby the filmadvance means. Preferably, the drive means provides for advancement offilm at first and second rates, and camera operating means are coupledto the drive means for selectively coupling the first or second drivemeans with the cam. Other drive means are coupled to the motor andadapted to be coupled to the movable lens element of the lens system.The drive means for the lens system is effective to adjust the movablelens element of the zoom lens system along its axes of movement in eachof two opposite directions. Control means are coupled to a lens drivemeans, and means are provided for effecting operation of the lens drivemeans from the motor independent of the operation of the drive means foradvancing film whereby the lens system can be adjusted from the motorthrough the third drive means without first coupling the first or seconddrive means to the motor.

The invention, and its objects and advantages, will become more apparentin the detailed description of the preferred embodiments presentedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of thepreferred embodiments of the invention presented below, reference ismade to the accompanying drawings, in which:

FIG. 1 is a fragmentary elevation view of a motion picture cameraillustrating a drive mechanism for a motion picture camera of thepresent invention and showing the parts in their rest position, i.e.,when neither the film advance means nor the drive for the zoom lenssystem is being operated from the motor;

FIG. 2 is a view similar to FIG. 1 but showing certain parts in a movedposition effected by the engagement of a camera operating means;

FIG. 3 is a view similar to FIG. 2 but showing the parts in the positionassumed after further movement of the camera operating means;

FIG. 4 is a view similar to FIG. 1 but illustrates the coupling of themotor to the zoom lens adjusting apparatus;

FIG. 5 is a view similar to FIG. 1 but showing the gears for the filmadvance means in a position that occasionally occurs;

FIG. 6 is a perspective view of certain elements of the drive mechanismof the invention;

FIG. 7 is an electrical schematic diagram of a control circuit for themechanism of the invention; and

FIGS. 8-10 are fragmentary views illustrating an embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Because motion picture camerasare well known, the present description will be directed in particularto elements forming part of, or cooperating more directly with, thepresent invention, elements not specifically shown or described hereinbeing understood to be selectable from those known in the art.

Referring now to the drawings in detail, a motion picture cameraincorporating the present invention com prises casing or mechanismplates generally designated 10 and 11. Plate 10 supports a suitable zoomlens system generally designated 12. The lens systems illustrated by wayof example comprises three lens elements 14, 16, 18 which define anoptical axis 20. The lens element 14 is normally stationary duringadjustment of the zoom lens system but may be movable for focusing andcertain manufacturing adjustments, if desired. At least one of theelements of the lens systems, for example the element 16, is supportedby a lens mount 22 for movement along the optical axis 20 in each of twoopposite directions for varying the magnification of the lens system.Lens mount 22 comprises a rack shown generally at 24 and having aplurality of teeth which are adapted to engage with teeth of a gear 26mounted on a shaft 28. Also mounted on shaft 28 is a second gear 30which is adapted to be driven from a suitable motor, such as an electricmotor 32. The coupling of the motor to the gear 30 is effected by aplurality of gears including a gear 34 mounted on motor shaft 36 whichis adapted to mesh with a relatively large gear 38 carried by a shaft40. Shaft 40 is carried by a generally triangular rocker plate 42 whichalso carries two shafts 44 and 46 for gears 48 and 50, respectively.Gears 48 and 50are in meshing engagement with each other, and gear 48 isadapted to be driven from a gear 52 which is mounted on shaft 40 andthereby driven from gear 38. Plate 42 is pivotably movable about theaxis of shaft 40 tobring either gear 48 or gear 50 into engagement withgear 30 on shaft 28. Because gear 48 and gear 50 are in engagement witheach other, they rotate in opposite directions so that the zoom lenssystem can be driven in either of two directions by selectively engaginggear 48 or gear 50 with gear 30. A clutch (not shown) can be provided inthe gear train between the motor and the adjustable lens element 16 topermit the drive for the element 16 to remain engaged after the elementhas reached the extreme limits of its movement.

The pivotal movement of plate 42 is controlled by means of a rod 56which has one end portion thereof pivotally connected at 58 to plate 42in spaced relation to the axis of shaft 40. The other end portion of rod56 is connected at 60 to an end portion of a lens operating controlmember 62, the latter being pivoted at 64 to mechanism plate 10. Thus,as shown in FIG. 4, when the right portion of the control member 62 isdepressed the plate 42 swings about the axis of shaft 40 to bring gear48 into engagement with gear 30 to drive the lens element 16 in onedirection. Similarly, depression of the left portion of lens controlmember 62 swings plate 42 in the opposite direction to bring the gear 52into engagement with the gear 30 thereby to reverse the movement of themovable lens element. Motor 32 can be energized to adjust the lenssystem independently of operation of the film advance mechanism byclosing of a normally open switch designated SW-l. Switch SW-l includesa movable contact member which is carried by a mid portion of rod 56 andis movable with the rod into engagement with either one of twostationary contacts 72a or 72b. Contacts 72a and 72b are electricallyinterconnected so that a circuit (described later) can be closed to themotor each time movable contact 70 is brought into engagement witheither of the stationary contacts. Switch SW-l is held in its normallyopen position by any suitable means, such as by a leaf spring 74 whichengages the lens control member 62 to hold it in position shown in FIG.1, thereby holding the switch in its open position.

The film advance mechanism for the camera includes a cam member showngenerally at which is positioned between mechanism plates 10 and 11 andis rotatably mounted on a cam shaft 82. In a manner well known in theart, one face of the cam (the face opposite from that shown in FIGS.1-6) can include both an edge cam surface 84 and a face cam surface (notshown). The face and edge cams are used for driving a claw in agenerally rectangular path so that the claw enters a perforation of afilm strip, advances the film strip a predetermined distance relative toan exposure aperture, and then withdraws from the film perforation andenters the next perforation, thereby intermittently advancing the filmpast the exposure aperture camera. Cam 80 has a plurality of'teeth 86about its outer periphery which are adapted to be engaged with gears fordriving the cam from motor 32. The face of cam 80 opposite from the faceand edge cams has a recess 88 formed therein comprising a generallycircular portion 88a which is coaxial with shaft 82 and an elongateextension or projecting portion 88b which communicates with portion 88abut is spaced from the axis of shaft 82 by a distance greater than theradius of circular portion of 88a. The purpose of the recess will bedescribed later.

Cam 80 is coupled to motor 32 by a gear train including two identicalgears 90 and 92 which are rotatably mounted on a plate 94 that ispivotal about the axis of shaft 36. The gear are spaced from each otherso that they are not in meshing engagement with each other. Gear 90meshes with gear 34 on the motor shaft 36 and gear 92 meshes with asmaller gear 96 on the motor shaft- Gears 90 and 92 are aligned in acommon plane with the teeth 86 on cam 80 so that either gear 90 or gear92 can be brought into meshing engagement with the teeth on the cam inresponse to pivotal movement of plate 94. Because gear 96 is smaller-indiameter than the gear 34, cam 80 is rotated at a faster rate by gear 90than by gear 92. Of course, the particular number of rpms imparted'tothe cam by each gear can be determined by the gear ratios and motorspeed. In a preferred embodiment, gears 90 and 92 are driven at rateswhich rotate cams to effect operation of the associated film pull downclaw (not shown) at rates of either 9 frames per second or 18 frames persecond, respectively. Both gears and 92 can be disengaged from gearteeth 86 as shown in FIG. 1 when the camera is not in operation or whenfilm is not being advanced, thereby permitting the single motor 32 to beused for driving the zoom lens mechanism as described hereinbefore.Also, it will be apparent that the zoom lens mechanism can be operatedin the manner described even when film is being advanced through thecamera since the coupling of the motor to the cam 80 is totallyindependent of the coupling of the motor to the zoom lens drive system.

Plate 94 has two tabs for lugs 95 and 97 which project outwardly awayfrom the face of the plate opposite from the gears 90 and 92. These tabsare located at the ends of fingers on the plate. A speed control member,generally designated 100, is substantially C-shaped in configuration,having a substantially semi-circular opening 100a. Notches 102 and 104in the speed control member face into opening 100a from opposite sidesthereof, and are of sufficient size to receive the tabs 95 and 97,respectively. As is apparent in FIGS. 1-5, the size of the opening 100ais sufficiently large so that only one tab 95 and 97 at a time can bepositioned in its respective notch in the control member. However, thecontrol member is adjustable in an up-anddown direction (as viewed inthe drawings) so that either of the tabs can be selectively positionedin its respective notch. The mounting of the control member whichpermits such movement comprises a pair of elongate guide slots 106 and108 in the control member which receive guide pins 110 and 112,respectively. The guide pins are mounted on and project upwardly from aface of a slider assembly generally designated 114. Control member 100can be held in either of its two adjusted positions by means of aflexible, generally V-shaped member 116 which is mounted on the sliderassembly 114 and which is adapted to engage each of a plurality ofnotches or detents 118 in a side edge of the control member. The controlmember can be manually moved by means of an integral knob portion 120that is conveniently located at the exterior of the camera. Suitableindicators 122 and 124 may be provided to designate to the cameraoperator the speed at which the camera is set to operate.

Control member 100 and slider assembly 114 are located above the uppersurface of mechanism plate 11. Slider assembly 114 is mountedon'mechanism plate 11 by means of two spaced guide pins and 132 whichproject from plate 11 into two elongate guide slots 134 and 136,respectively in the slider assembly. This mounting permits the entireassembly 114 with the control member 100 thereon to be shifted to theright from the position shown in FIG. 1 through the position shown inFIG. 2 to the position shown in FIG. 3. During such movement of assembly114 control member 100 engages one or the other of the tabs 95 or 97 toeffect pivotal movement of plate 94 and thereby bringing one of thegears 90 or 92 into meshing engagement with the gear teeth 86 on thecam. This is illustrated in FIGS. l3 for movement of gear 92 intoengagement with cam gear teeth. Gear 90 is moved into engagement withthe cam gear teeth by shifting control member 100 downwardly from itsFIG. 1 position and then moving 'slider assembly 114 to the right.

to the right as viewed in the drawings. This can be effected by manuallydepressing the left end portion of the lever which is convenientlylocated at the exterior of the camera. Lever is mounted for slidingmovement with respect to the mechanism plate 11 by a pair of mountingpins 142 and 144 on plate 11 which project upwardly into elongate slots146 and 148, respectively, in lever 140. Lever 140 is urged to theposition as shown in FIG. 1 by a tension spring 150 which is stretchedbetween the pin 142 and a tab 152 on the lever.

Lever 140 has a finger portion 154 at its right end that is offsetupwardly from other portions of the lever, and a lug 156 on the fingeris adapted to engage one side edge of a cooperating, downwardlyprojecting finger portion 158 on the slider assembly 114. Thus thebiasing force of spring 150 is imparted through lug 156 to finger 158 tourge the slider assembly 114 into the position illustrated in FIG. 1.Lever 140 and assembly 1 14 are resiliently connected together formovement to the right from the FIG. 1 position to the FIG. 3 position bymeans of a tension spring 160 which is connected to and stretchedbetween the finger portion 154 of lever 140 and the finger portion 158of assembly 114. Thus depression of trigger 140 (movement to the right)produces a biasing force urging the assembly 114 to the right; however,lever 140 can be moved to the right by the operator withoutcorresponding movement of assembly 114 by simply stretching or furthertensioning spring 160.

As is well known in the art, it is desirable to stop the shutter (notshown) of the camera in a position for blocking passage of light fromthe lens system to film located in the exposure plane of the camera,thereby avoiding continuous exposure of film when the camera is not inuse. The illustrated structure for accomplishing this comprises a lever162 which is mounted on pin 132 beneath slider 114 for pivotal movementabout the axis of the pin. Projecting downwardly from one side edge ofthe lever 162 is a lug 164 which extends through an opening 165 in plate1 1 and into the straight portion 88b of the recess in the cam 80 whenthe parts are positioned as illustrated in FIG. 1. The stop 164interferes with rotation of the cam, thereby preventing rotation ofshaft 82 on which the shutter is mounted. However, movement of stop 164to the position shown in FIG. 3, where it is in alignment with thecircular portion 88a of the recess in the cam, permits unrestrictedrotation of the cam (and thus shaft 82) for advancement of the filmthrough the camera. Lever 162 normally is biased to the position shownin FIG. 1 by a spring 166 which is connected to the lever and to plate11. However, the lever can be swung counterclockwise about the axis ofpin 132 in response to engagement between the finger portion of 154 ofthe trigger lever 140 and a flange portion 168 on the end portion oflever 162 opposite from stop 164. This movement is best illustrated bycomparison of the phantom-line and solidline positions for lever 162 inFIG. 3.

When trigger 140 is released to terminate a filming sequence, rotationof the cam should be continued until the shutter returns to a positionalong the light path between the lens system of the camera and the filmplane. Also, motor 32 should be de-energized when stop 164 is in recessportion 88b. This is accomplished by cooperation between stop 164 andthe circular recess 88a, and by operation of a second switch SW-2.Switch SW-2 comprises a first contact member 170 formed by a flange onthe end portion of lever 162 and by a flexible switch contact 172 whichis connected in circuit to the motor and to a power source as explainedlater. The contact members 170 and 172 .are positioned with respect toeach other so that switch SW-2 is closed as stop 164 moves from therecess portion 88b into the circular recess portion 88a so that theswitch SW-2 can complete a circuit to the motor to initiate operation ofthe motor and rotation of the cam at approximately the same time thestop enters the circular recess portion. Operation of the motor willcontinue until switch SW-2 is opened, and this occurs when (l) triggerfinger 154 moves to the left (away from flange 168), and (2) the camrotates to a position where stop 164 is aligned with the recess 88b,thereby permitting movement of the stop into the elongated recessportion 88b under the biasing force of spring 166.

Whilestop 164 maintains switch SW-2 in a closed condition until theshutter returns to the correct position for terminating exposure of thefllm, it is also necessary to maintain engagement between one of thegears 90 and 92 and the gear teeth 86 on the cam after the trigger lever140 has been released by the camera operator. Failure to do this wouldresult in the motor remaining energized because switch SW-2 was closed,but the motor would be ineffective to continue driving of the cam tobring the stop tothe position where it can return to the elongatedportion of the recess and slider assembly can be moved freely from theposition.

shown in'FIG. 1 to the position shown in FIG. 2 when the lever is in theposition illustrated in those views wherein the stop 164 is in theelongate portion 88b of the recess. However, when the lever 162 moves tothe position illustrated in FIG.'3, the latch surface 178 swings intothe path of movement of the lug 176 to prevent return movement of theslider assembly 114 to the positionshown in FIG. 1. This blockingrelation ends when the lever 162 returns to its FIG. 1 position, therebymoving surface 178 out of the path of lug 176.

Lever 162 has an edge 177 adjacent latch surface 178 which is positionedwith respect to lug 176 to prevent movement of the lever to its FIG.,3position until the slider moves part of the way from its FIG. 1 positionto its FIG. 3 position. This insures the closing of a switch SW-3(described later) before lever'162 can move to close switch SW-2.

FIG. 7 illustrates an electrical schematic diagram suitable forinterconnecting the various electrically controlled portions of thecamera to effect the mode of operation described herein. Current isprovided from a suitable source of electric power, such as a battery190. A circuit is coupled from the battery through motor 32 wheneverswitch SW-2 is closed. Assuming an exposure control system is providedfor the camera, it is desirable to energize the exposure control systemprior to the time switch SW-2 is closed to begin operation of the pulldown mechanism. The switch designated SW-3 is provided for this purpose.The switch is connected in a circuit including battery 190 and theexposure control system designated 192, the circuit being connected inparallel to motor 32 and switch SW-2. The desired sequence of operationis effected by providing for clo sure of switch SW-3 shortly beforeclosing of switch SW-2. As illustrated in FIGS. 1-4, switch SW-3includes a fixed contact 194 and a movable contact 196, the switchnormally being open when the camera is not being operated due toengagement between the left end of slider assembly 114 and the movablecontact 196. As the slider assembly begins its movement from its FIG. 1to its FIG. 2 position, and before the assembly reaches a position wherelug 176 is out of the way of edge 177 of lever 162, the movable contact196 is closed to the fixed contact 194 to complete the circuit to theexposure control system. This permits correct exposure of the firstframe of film.

Switch SW-l is connected in parallel to switches SW-2 and SW-3 and tothe exposure control system 192. Switch SW-l is connected in a circuitwhich includes motor 32 and battery 190 so that the closing of switchSW-l normally operates the motor to drive the gears that can be coupledto the zoom drive mechanism.

In order to facilitate engagement between the gears or 92 and the gearteeth 86 on the cam, it is preferred that the gears not be rotatedduring the engagement of such gears. This, of course, requires that themotor be de-energized. This is assured by the provision of a switchdesignated SW-4 in FIGS. 1-5 and 7 which is normally closed but can beopened just prior to engagement of gears 90 or 92 with the gear teeth onthe cam. As shown in FIGS. 14, this is accomplished by utilizing themovable contact 196 forming part of switch SW-3 and another fixedcontact designated 198, and locating the contact 198 with respect tomovable contact 196 so that switch SW-4 is normally closed when theslider assembly is in its FIG. 1 position. Switch SW-4 will remainclosed until the slider assembly begins its movement from the FIG. 1position and reaches its FIG. 2 position at which time the movablecontact 196 becomes disengaged from fixed contact .198 and moves incontact with the contact 194 to close switch SW-3. With switch SW-4open, the motor can only be energized by closing switch SW-2, and thisnormally does not occur until after the gears 90, 92 mesh with gearteeth 86.

After switch SW-4 opens, and before switch SW-2 closes, there is aninstant of time when the camera operator cannot operate the zoom lensdrive mechanism even though operator 62 is'depressed. This, however, isordinarily an extremely brief period of time, and may not even benoticed by the camera operator. Thus if the zoom lens drive is engagedand the motor running at the time the operator moves lever to initiateadvancement of film, switch SW-4 opens to briefly stop motor 32 butswitch SW-2 normally is closed an instant later to again start themotor. Thus if the operator continues to press the zoom control member62, the zoom lens will momentarily pause and then continue its movement.Of course, after the switch SW-2 is closed,

switch SW-4 may remain open since there is no longer any need to useswitch SW-l to adjust the lens system. In other words, after the motoris energized through switch SW-Z, adjustment of the lens system requiresonly a mechanical operation that is independent of the closing of switchSW-l.

The operation of the camera of the invention will now be summarized.Initially it will be assumed that the various parts are in the positionillustrated in FIG. 1 where both the zoom lens drive mechanism and thefilm advance mechanism are at rest and the exposure control system isde-energized. Thus switches SW-l, SW-2, and SW-3 are open and switch SW4is closed. Referring to FIG. 4, if the camera operator wishes to adjustthe zoom lens mechanism without effecting advancement of film throughthe camera, the control member 62 is depressed to rock plate 42 and toclose switch SW-1, thereby energizing the motor and driving gears 48 and50 through the gear train described hereinbefore. The zoom drivemechanism is then driven in either one of two opposite directions,depending upon which one of the gears 48 or 50 is engaged with gear 30.(FIG. 4 illustrates gear 48 engaged with gear 30.) Movement of the zoomlens mechanism continues until the control member is released or untilthe rack 24 reaches one extreme end of its movement where the clutch(not shown) in the gear train begins to slip.

Assuming now that the various parts are in the position illustrated inFIG. 1 and that the camera operator desires to operate the film pulldown mechanism without adjustment of the zoom lens. The operator firstdetermines the rate at which film will be advanced in the camera bymoving the speed control member 100 to the position shown in FIGS. 1-5or to its other position (not shown) wherein tab 97 is positioned withinthe confines of notch 104. Then the operator depresses the trigger lever140 to effect its movement from the position shown in FIG. 1 through theposition shown in FIG. 2 to the position shown in FIG. 3. As thisoccurs, spring 160 biases the slider assembly 114 to the right from itsFIG. 1 position for opening switch SW-4 and closing switch SW-3, therebynormally to energize the exposure control system before exposure of filmbegins. This travel of the lever 140 brings the finger portion 154thereof into engagement with the portion 168 of lever 162 to urge lever162 about the axis of pin 132. However, movement of the lever 162 cannotoccur (due to the tab 176 on the slider assembly) until the sliderassembly 114 moves to the right to close switch SW-3. After tab 176 ismoved to the right with the slider assembly to a point that permitspivotal movement of the lever 162, the lever swings to the positionshown in solid lines in FIG. 3 against the bias of spring 166 to bringthe stop 164 out of the elongated portion 88b of the recess and into thecircular portion 88a. Simultaneously, switch SW-2 is closed, therebyenergizing the motor 32 to drive gears 90 and 92.

As the slider assembly 114 moves to the right it engages one of the tabs95 or 97 on plate 94, therebyswinging the plate about the axis of shaft36 to bring gear 92 or gear 90 into engagement with the teeth 86 fordriving the film pull down mechanism. Normally, the gears become engagedbefore the closing of switch SW-2 to avoid any difficulty that mightresult from trying to mesh gear 90 or 92 while they are rotating andwhile the gear teeth 86 are stationary. With motor 32 running and filmbeing advanced in the manner de- I urged to its FIG. 1 position byspring 150. Lever 162 can then return to its FIG. 1 position. Slider 114is moved to the left by tab 156 on lever 140 which engages the sliderfinger 158 and moves the slider with the lever.

Ordinarily the teeth 86 on cam and the teeth on gears 90 and 92 will bebrought into meshing engagement with each other in response to themovement of plate 94 in the manner described hereinbefore. However, thegear teeth may be positioned with respect to each other so that the gearteeth do not mesh, i.e., the outer extremities of the teeth 86 areengaged by the outer extremities of the teeth on gear 90 and 92, suchbeing illustrated in FIG. 5 of the drawings. This relative positionbetween the gear teeth could be changed by releasing the lever andengaging the mechanism for adjusting zoom lens system since suchadjustment also effects rotation of gears 90 and 92. However, with themechanism of the invention this is not necessary because, after initialmovement of slider assembly 114, the lever 140 can engage and move lever162 to close switch SW-2 and energize the motor. When the motor isenergized, gears 90 and 92 are rotated to bring the gear teeth intomeshing engagement with teeth 86. This is made possible by the springwhich establishes an elastic connection between lever 140 and sliderassembly 114.

Referring now to the embodiment of the invention illustrated in FIGS.8-10, a slider assembly generally designated 210 is similar to theassembly 1 14 described hereinbefore. Thus assembly 210 is resilientlyurged to the right by spring means (such as spring 160) in response tothe camera operator depressing lever 140, and the assembly is urged tothe left upon release of lever 140 by the biasing force exerted by aspring shown diagrammatically at 212. Movement of the slider assembly tothe right is limited by a stop 214 which projects through an opening 216in slider assembly 210, the stop being mounted on mechanism plate 11,for example. Movement of the slider assembly to the position illustratedin FIG. 9 closes a switch designated SW-3a comprising a contact member218 mounted on a suitable support member 220 and a contact memberdefined by the right end 222 of the slider assembly. Switch SW-3a isconnected in a circuit to the exposure control system of the camera inthe manner described hereinbefore in connection with switch SW-3.

Slider assembly 210 has a notch 224 which opens to its left end and iselongated in the same direction as the slider normally moves. A lever226 is mounted on a pin 228 for pivotal movement about the axis of thepin. A tab 230 at one end of lever 226 projects upwardly into the notch224 in the slider assembly when the slider assembly is in the positionillustrated in FIG. 8. The edge 224a of notch 224 preventscounterclockwise movement of the lever 226 about pin 228 until such timeas the slider assembly moves to the right past its FIG. 9 position toits FIG. 10 position. The length of notch 224 in slider assembly 210 issuch that the switch SW-3a is closed before the tab 230 is clear of theleft end of the notch. The lever is urged upwardly by a springdiagrammatically shown at 232.

Another lever 234 is mounted on pin 228 beneath lever 226 for pivotalmovement about the pin. Lever 234 comprises a tab 236 defining a switchcontact which is engageable with another switch contact 238 mounted onsupport 220 when the lever swings from its FIG. 8 to its FIG. position.Contacts 236 and 238 define a switch SW-2a that can be connected in acircuit to motor 32 in a manner shown for switch SW-2 in FIG. 7. A lug237 on lever 234 projects upwardly from the lower side edge of the leverinto the plane of lever 226 and adjacent the upper edge of lever 226 sothat the lever 226 is moved clockwise with lever 234 as the lever 234 isswung from its FIG. 10 to its FIG. 8 position.

Lever 234 includes a tab 240 which projects downwardly through opening165 in plate 11. Tab 240, like tab 164, cooperates with recessed portion88 in cam 80 to permit the cam to stop only when the shutter is acrossthe optical path and between the lens system and the film.

Lever 234 has a flange 239 projecting into the path of movement offinger 154 of the trigger lever 140 so that the lever is swung from itsFIG. 8 to its FIG. 10 position when the trigger lever is depressed. Thevarious parts are arranged with respect to eachother so that normallythe slider 210 moves to close switch SW-3a, then lever 234 is swung toits FIG. 10 position (closing switch SW-Za), and then lever 226 isreleased by slider 210 and swung by spring 232 to the position shown inFIG. 10 wherein lever 226 blocks movement of slider 210 to the left (andthereby prevents uncoupling of the gear drive to cam 80) until tab 240enters recess portion 88b on the cam under the influence of spring 244.

When trigger lever 140 is released at the end of a sequence of filming,slider assembly 210 is urged to left by spring 212. Such movement of theslider assembly is prevented initially due to the engagement between thetab 230 on lever 226 and the edge 233 of the slider assembly immediatelyabove the notch 224. However, when the lug 240 on lever 234 becomesaligned with the portion 88b of the recess in the cam, lever 234 swingsto the right under the influence of spring 244 to bring the tab into therecess portion 88b. As this clockwise motion of lever 234 occurs, switchSW 2a is opened, and the lug 237 on lever 234 moves lever 226 downwardlyfrom its FIG. 10 position to its FIG. 8 position, thereby bringing thetab 230 into alignment with the notch 224. This releases the sliderassembly 210 and permits it to move to the left under the biasing forceexerted by spring 212. Thus the slider assembly returns to its FIG. 8position and switch SW-3a is opened. This movement of the sliderassembly disengages gears 90 or 92 from the gear teeth on the cammember.

Because levers 226 and 234 are independently movable in acounterclockwise direction as explalned hereinbefore, lever 234 can beswung to the position illustrated in FIG. 10 to close switch SW-Za andthereby energize motor 32 for driving gears 90 or 92 even in those raresituations when the tops of the gear teeth engages each other as shownin FIG. 5 rather than mesh in a normal driving relation. In the absenceof such independent movement, the slider assembly 210 could not move tothe right by a sufficient distance to permit lever 226 to move upwardlyuntil such time as the gears properly meshed. This avoids the necessityof having to drive gear or 92 by operation of the zoom drive mechanismin order to adjust the relative position of gear teeth with the teeth 86on the cam. Also, the drive for the film advance mechanism can be usedon cameras that do not incorporate zoom drive mechanisms, thereby makingvery desirable the provisions of some means (such as shown in FIG. 8-10)for independently operating the motor before meshing engagement of thegears occurs.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

1. In a drive mechanism for a motion picture camera having a motoradapted to drive a gear, a cam member having a plurality of gear teeththereon engageable by the gear for rotation of the cam member, andautomatic exposure control means, the improvement comprising:

first and second normally open switches connected'in a circuit forselectively energizing the motor and the exposure control means,respectively, from a source of electrical potential, each of saidswitches comprising first and second switch contacts with the firstswitch contact of each switch being mounted in a predetermined positionwithin the camera; and

control means for sequentially closing said switches to permitenergization of the exposure control means before the motor is energizedto drive the cam, said control means comprising a. a trigger membermounted on the camera for movement between a first position and a secondposition, i

b. a slider member mounted on the camera for movement between a firstposition and a second position, one portion of said slider member defin-'ing the second contact of the second switch, said one portion of theslider member being engageable with the first contact of the secondswitch in response to movement of the slider member from its firstposition to its second position and disengageable from said firstcontact in response to movement of the slider member from its secondposition to its first position,

0. spring means coupled to said trigger member and to said slider memberfor effecting a resilient connection between said members which urgessaid slider member toward its second position in response to movement ofthe trigger member to its second position,

d. means coupled to the trigger member and the slider member for urgingthem from their second positions to their first positions when thetrigger member is released,

e. first and second levers pivotally mounted on the camera for movementbetween first and second positions, said first lever having a firstportion positioned with respect to the trigger member to be engaged bythe trigger member as it moves from its first position to its secondposition to effect pivotal movement of the first lever from its firstposition to its second position, said first lever having a secondportion defining the second switch contact member of the first switch,said second portion of the first lever being out of engagement with thefirst contact of the first switch when the first lever is in its firstposition and being engageable with such contact when the lever is in itssecond position, said second lever and said slider member havingcooperating portions operable (1 to hold said second lever in its firstposition until the second switch is closed in response to movement ofthe slider member toward its second position, and (2) to hold saidslider member against return from its second position to its firstposition until the second lever returns to its first position.

2. In a mechanism as set forth in claim 1, the improvement comprisingspring means urging said second lever from its first position to itssecond position, and means responsive to movement of said first leverfrom its second position to its first position for moving said secondlever from its second position to its first position against said springmeans.

3. In a mechanism as set forth in claim 1 further comprising cooperatingmeans on the cam and on the first lever for 1 preventing movement of thecam until the first lever moves from its first position to its secondposition and (2) holding the first lever in its second position untilthe cam is located in a particular orientation relative to the firstlever, and spring means biasing said first lever from its secondposition to its first position.

1. In a drive mechanism for a motion picture camera having a motoradapted to drive a gear, a cam member having a plurality of gear teeththereon engageable by the gear for rotation of the cam member, andautomatic exposure control means, the improvement comprising: first andsecond normally open switches connected in a circuit for selectivelyenergizing the motor and the exposure control means, respectively, froma source of electrical potential, each of said switches comprising firstand second switch contacts with the first switch contact of each switchbeing mounted in a predetermined position within the camera; and controlmeans for sequentially closing said switches to permit energization ofthe exposure control means before the motor is energized to drive thecam, said control means comprising a. a trigger member mounted on thecamera for movement between a first position and a second position, b. aslider member mounted on the camera for movement between a firstposition and a second position, one portion of said slider memberdefining the second contact of the second switch, said one portion ofthe slider member being engageable with the first contact of the secondswitch in response to movement of the slider member from its firstposition to its second position and disengageable from said firstcontact in response to movement of the slider member from its secondposition to its first position, c. spring means coupled to said triggermember and to said slider member for effecting a resilient connectionbetween said members which urges said slider member toward its secondposition in response to movement of the trigger member to its secondposition, d. means coupled to the trigger member and the slider memberfor urging them from their second positions to their first positionswhen the trigger member is released, e. first and second leverspivotally mounted on the camera for movement between first and secondpositions, said first lever having a first portion positioned withrespect to the trigger member to be engaged by the trigger member as itmoves from its first position to its second position to effect pivotalmovement of the first lever from its first position to its secondposition, said first lever having a second portion defining the secondswitch contact member of the first switch, said second portion of thefirst lever being out of engagement with the first contact of the firstswitch when the first lever is in its first position and beingengageable with such contact when the lever is in its second position,said second lever and said slider member having cooperating portionsoperable (1) to hold said second lever in its first position until thesecond switch is closed in response to movement of the slider membertoward its second position, and (2) to hold said slider member againstreturn from its second position to its first position until the secondlever returns to its first position.
 2. In a mechanism as set forth inclaim 1, the improvement comprising spring means urging said secondlever from its first position to its second position, and meansresponsive to movement of said first lever from its second position toits first position for moving said second lever from its second positionto its first position against said spring means.
 3. In a mechanism asset forth in claim 1 further comprising cooperating means on the cam andon the first lever for (1) preventing movement of the cam until thefirst lever moves From its first position to its second position and (2)holding the first lever in its second position until the cam is locatedin a particular orientation relative to the first lever, and springmeans biasing said first lever from its second position to its firstposition.